If you’re not already running an ad blocker I highly recommend you start. In addition to reducing bandwidth usage ad blockers also protect against ad network delivered malware. Because they span so many separate websites ad networks are common targets for malicious hackers. When they find an exploit they usually use the compromised network to deliver malware to users who access websites that rely on the ad network. Yahoo’s network is the most recent example of this scenario:

June and July have set new records for malvertising attacks. We have just uncovered a large scale attack abusing Yahoo!’s own ad network.

As soon as we detected the malicious activity, we notified Yahoo! and we are pleased to report that they took immediate action to stop the issue. The campaign is no longer active at the time of publishing this blog.

This latest campaign started on July 28th, as seen from our own telemetry. According to data from SimilarWeb, Yahoo!’s website has an estimated 6.9 Billion visits per month making this one of the largest malvertising attacks we have seen recently.

When a single ad network can see almost 7 billion visits per month it’s easy to see why malware distributors try to exploit them.

Many websites rely on advertisements for revenue so they understandably get upset when users visit their pages while using ad blockers. But their revenue model requires their users put themselves at risk so I don’t have any sympathies. If you run a website that relies on ads you should be looking at different revenue models, preferable ones that don’t put your users in harm’s way.